This invention relates to an undercut beneath the platform of a trailing edge of a turbine blade, wherein the undercut has a shape designed to move stress concentration away from the platform.
Turbine blades typically include a platform, with an airfoil extending outwardly of the platform. The airfoil and platform are exposed to thermal stress, as they come into contact with heated gasses. The thermal stresses create design challenges for the platform.
One method of reducing stress at the platform is the formation of an undercut at a trailing edge of the platform. The prior art undercut has generally been on a single radius. While the known undercut does reduce stress concentration, the single radius leaves a highly stressed area adjacent the portion of the radius merging into the platform.